1//===- DWARFDebugLoc.cpp --------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
10#include "llvm/ADT/StringRef.h"
11#include "llvm/BinaryFormat/Dwarf.h"
12#include "llvm/DebugInfo/DIContext.h"
13#include "llvm/DebugInfo/DWARF/DWARFAddressRange.h"
14#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
15#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
16#include "llvm/DebugInfo/DWARF/DWARFLocationExpression.h"
17#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
18#include "llvm/Support/Format.h"
19#include "llvm/Support/raw_ostream.h"
20#include <algorithm>
21#include <cinttypes>
22#include <cstdint>
23
24using namespace llvm;
25using object::SectionedAddress;
26
27namespace llvm {
28class DWARFObject;
29}
30
31namespace {
32class DWARFLocationInterpreter {
33  std::optional<object::SectionedAddress> Base;
34  std::function<std::optional<object::SectionedAddress>(uint32_t)> LookupAddr;
35
36public:
37  DWARFLocationInterpreter(
38      std::optional<object::SectionedAddress> Base,
39      std::function<std::optional<object::SectionedAddress>(uint32_t)>
40          LookupAddr)
41      : Base(Base), LookupAddr(std::move(LookupAddr)) {}
42
43  Expected<std::optional<DWARFLocationExpression>>
44  Interpret(const DWARFLocationEntry &E);
45};
46} // namespace
47
48static Error createResolverError(uint32_t Index, unsigned Kind) {
49  return make_error<ResolverError>(Index, (dwarf::LoclistEntries)Kind);
50}
51
52Expected<std::optional<DWARFLocationExpression>>
53DWARFLocationInterpreter::Interpret(const DWARFLocationEntry &E) {
54  switch (E.Kind) {
55  case dwarf::DW_LLE_end_of_list:
56    return std::nullopt;
57  case dwarf::DW_LLE_base_addressx: {
58    Base = LookupAddr(E.Value0);
59    if (!Base)
60      return createResolverError(E.Value0, E.Kind);
61    return std::nullopt;
62  }
63  case dwarf::DW_LLE_startx_endx: {
64    std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
65    if (!LowPC)
66      return createResolverError(E.Value0, E.Kind);
67    std::optional<SectionedAddress> HighPC = LookupAddr(E.Value1);
68    if (!HighPC)
69      return createResolverError(E.Value1, E.Kind);
70    return DWARFLocationExpression{
71        DWARFAddressRange{LowPC->Address, HighPC->Address, LowPC->SectionIndex},
72        E.Loc};
73  }
74  case dwarf::DW_LLE_startx_length: {
75    std::optional<SectionedAddress> LowPC = LookupAddr(E.Value0);
76    if (!LowPC)
77      return createResolverError(E.Value0, E.Kind);
78    return DWARFLocationExpression{DWARFAddressRange{LowPC->Address,
79                                                     LowPC->Address + E.Value1,
80                                                     LowPC->SectionIndex},
81                                   E.Loc};
82  }
83  case dwarf::DW_LLE_offset_pair: {
84    if (!Base) {
85      return createStringError(inconvertibleErrorCode(),
86                               "Unable to resolve location list offset pair: "
87                               "Base address not defined");
88    }
89    DWARFAddressRange Range{Base->Address + E.Value0, Base->Address + E.Value1,
90                            Base->SectionIndex};
91    if (Range.SectionIndex == SectionedAddress::UndefSection)
92      Range.SectionIndex = E.SectionIndex;
93    return DWARFLocationExpression{Range, E.Loc};
94  }
95  case dwarf::DW_LLE_default_location:
96    return DWARFLocationExpression{std::nullopt, E.Loc};
97  case dwarf::DW_LLE_base_address:
98    Base = SectionedAddress{E.Value0, E.SectionIndex};
99    return std::nullopt;
100  case dwarf::DW_LLE_start_end:
101    return DWARFLocationExpression{
102        DWARFAddressRange{E.Value0, E.Value1, E.SectionIndex}, E.Loc};
103  case dwarf::DW_LLE_start_length:
104    return DWARFLocationExpression{
105        DWARFAddressRange{E.Value0, E.Value0 + E.Value1, E.SectionIndex},
106        E.Loc};
107  default:
108    llvm_unreachable("unreachable locations list kind");
109  }
110}
111
112static void dumpExpression(raw_ostream &OS, DIDumpOptions DumpOpts,
113                           ArrayRef<uint8_t> Data, bool IsLittleEndian,
114                           unsigned AddressSize, DWARFUnit *U) {
115  DWARFDataExtractor Extractor(Data, IsLittleEndian, AddressSize);
116  // Note. We do not pass any format to DWARFExpression, even if the
117  // corresponding unit is known. For now, there is only one operation,
118  // DW_OP_call_ref, which depends on the format; it is rarely used, and
119  // is unexpected in location tables.
120  DWARFExpression(Extractor, AddressSize).print(OS, DumpOpts, U);
121}
122
123bool DWARFLocationTable::dumpLocationList(
124    uint64_t *Offset, raw_ostream &OS, std::optional<SectionedAddress> BaseAddr,
125    const DWARFObject &Obj, DWARFUnit *U, DIDumpOptions DumpOpts,
126    unsigned Indent) const {
127  DWARFLocationInterpreter Interp(
128      BaseAddr, [U](uint32_t Index) -> std::optional<SectionedAddress> {
129        if (U)
130          return U->getAddrOffsetSectionItem(Index);
131        return std::nullopt;
132      });
133  OS << format("0x%8.8" PRIx64 ": ", *Offset);
134  Error E = visitLocationList(Offset, [&](const DWARFLocationEntry &E) {
135    Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
136    if (!Loc || DumpOpts.DisplayRawContents)
137      dumpRawEntry(E, OS, Indent, DumpOpts, Obj);
138    if (Loc && *Loc) {
139      OS << "\n";
140      OS.indent(Indent);
141      if (DumpOpts.DisplayRawContents)
142        OS << "          => ";
143
144      DIDumpOptions RangeDumpOpts(DumpOpts);
145      RangeDumpOpts.DisplayRawContents = false;
146      if (Loc.get()->Range)
147        Loc.get()->Range->dump(OS, Data.getAddressSize(), RangeDumpOpts, &Obj);
148      else
149        OS << "<default>";
150    }
151    if (!Loc)
152      consumeError(Loc.takeError());
153
154    if (E.Kind != dwarf::DW_LLE_base_address &&
155        E.Kind != dwarf::DW_LLE_base_addressx &&
156        E.Kind != dwarf::DW_LLE_end_of_list) {
157      OS << ": ";
158      dumpExpression(OS, DumpOpts, E.Loc, Data.isLittleEndian(),
159                     Data.getAddressSize(), U);
160    }
161    return true;
162  });
163  if (E) {
164    DumpOpts.RecoverableErrorHandler(std::move(E));
165    return false;
166  }
167  return true;
168}
169
170Error DWARFLocationTable::visitAbsoluteLocationList(
171    uint64_t Offset, std::optional<SectionedAddress> BaseAddr,
172    std::function<std::optional<SectionedAddress>(uint32_t)> LookupAddr,
173    function_ref<bool(Expected<DWARFLocationExpression>)> Callback) const {
174  DWARFLocationInterpreter Interp(BaseAddr, std::move(LookupAddr));
175  return visitLocationList(&Offset, [&](const DWARFLocationEntry &E) {
176    Expected<std::optional<DWARFLocationExpression>> Loc = Interp.Interpret(E);
177    if (!Loc)
178      return Callback(Loc.takeError());
179    if (*Loc)
180      return Callback(**Loc);
181    return true;
182  });
183}
184
185void DWARFDebugLoc::dump(raw_ostream &OS, const DWARFObject &Obj,
186                         DIDumpOptions DumpOpts,
187                         std::optional<uint64_t> DumpOffset) const {
188  auto BaseAddr = std::nullopt;
189  unsigned Indent = 12;
190  if (DumpOffset) {
191    dumpLocationList(&*DumpOffset, OS, BaseAddr, Obj, nullptr, DumpOpts,
192                     Indent);
193  } else {
194    uint64_t Offset = 0;
195    StringRef Separator;
196    bool CanContinue = true;
197    while (CanContinue && Data.isValidOffset(Offset)) {
198      OS << Separator;
199      Separator = "\n";
200
201      CanContinue = dumpLocationList(&Offset, OS, BaseAddr, Obj, nullptr,
202                                     DumpOpts, Indent);
203      OS << '\n';
204    }
205  }
206}
207
208Error DWARFDebugLoc::visitLocationList(
209    uint64_t *Offset,
210    function_ref<bool(const DWARFLocationEntry &)> Callback) const {
211  DataExtractor::Cursor C(*Offset);
212  while (true) {
213    uint64_t SectionIndex;
214    uint64_t Value0 = Data.getRelocatedAddress(C);
215    uint64_t Value1 = Data.getRelocatedAddress(C, &SectionIndex);
216
217    DWARFLocationEntry E;
218
219    // The end of any given location list is marked by an end of list entry,
220    // which consists of a 0 for the beginning address offset and a 0 for the
221    // ending address offset. A beginning offset of 0xff...f marks the base
222    // address selection entry.
223    if (Value0 == 0 && Value1 == 0) {
224      E.Kind = dwarf::DW_LLE_end_of_list;
225    } else if (Value0 == (Data.getAddressSize() == 4 ? -1U : -1ULL)) {
226      E.Kind = dwarf::DW_LLE_base_address;
227      E.Value0 = Value1;
228      E.SectionIndex = SectionIndex;
229    } else {
230      E.Kind = dwarf::DW_LLE_offset_pair;
231      E.Value0 = Value0;
232      E.Value1 = Value1;
233      E.SectionIndex = SectionIndex;
234      unsigned Bytes = Data.getU16(C);
235      // A single location description describing the location of the object...
236      Data.getU8(C, E.Loc, Bytes);
237    }
238
239    if (!C)
240      return C.takeError();
241    if (!Callback(E) || E.Kind == dwarf::DW_LLE_end_of_list)
242      break;
243  }
244  *Offset = C.tell();
245  return Error::success();
246}
247
248void DWARFDebugLoc::dumpRawEntry(const DWARFLocationEntry &Entry,
249                                 raw_ostream &OS, unsigned Indent,
250                                 DIDumpOptions DumpOpts,
251                                 const DWARFObject &Obj) const {
252  uint64_t Value0, Value1;
253  switch (Entry.Kind) {
254  case dwarf::DW_LLE_base_address:
255    Value0 = Data.getAddressSize() == 4 ? -1U : -1ULL;
256    Value1 = Entry.Value0;
257    break;
258  case dwarf::DW_LLE_offset_pair:
259    Value0 = Entry.Value0;
260    Value1 = Entry.Value1;
261    break;
262  case dwarf::DW_LLE_end_of_list:
263    return;
264  default:
265    llvm_unreachable("Not possible in DWARF4!");
266  }
267  OS << '\n';
268  OS.indent(Indent);
269  OS << '(' << format_hex(Value0, 2 + Data.getAddressSize() * 2) << ", "
270     << format_hex(Value1, 2 + Data.getAddressSize() * 2) << ')';
271  DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
272}
273
274Error DWARFDebugLoclists::visitLocationList(
275    uint64_t *Offset, function_ref<bool(const DWARFLocationEntry &)> F) const {
276
277  DataExtractor::Cursor C(*Offset);
278  bool Continue = true;
279  while (Continue) {
280    DWARFLocationEntry E;
281    E.Kind = Data.getU8(C);
282    switch (E.Kind) {
283    case dwarf::DW_LLE_end_of_list:
284      break;
285    case dwarf::DW_LLE_base_addressx:
286      E.Value0 = Data.getULEB128(C);
287      break;
288    case dwarf::DW_LLE_startx_endx:
289      E.Value0 = Data.getULEB128(C);
290      E.Value1 = Data.getULEB128(C);
291      break;
292    case dwarf::DW_LLE_startx_length:
293      E.Value0 = Data.getULEB128(C);
294      // Pre-DWARF 5 has different interpretation of the length field. We have
295      // to support both pre- and standartized styles for the compatibility.
296      if (Version < 5)
297        E.Value1 = Data.getU32(C);
298      else
299        E.Value1 = Data.getULEB128(C);
300      break;
301    case dwarf::DW_LLE_offset_pair:
302      E.Value0 = Data.getULEB128(C);
303      E.Value1 = Data.getULEB128(C);
304      E.SectionIndex = SectionedAddress::UndefSection;
305      break;
306    case dwarf::DW_LLE_default_location:
307      break;
308    case dwarf::DW_LLE_base_address:
309      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
310      break;
311    case dwarf::DW_LLE_start_end:
312      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
313      E.Value1 = Data.getRelocatedAddress(C);
314      break;
315    case dwarf::DW_LLE_start_length:
316      E.Value0 = Data.getRelocatedAddress(C, &E.SectionIndex);
317      E.Value1 = Data.getULEB128(C);
318      break;
319    default:
320      cantFail(C.takeError());
321      return createStringError(errc::illegal_byte_sequence,
322                               "LLE of kind %x not supported", (int)E.Kind);
323    }
324
325    if (E.Kind != dwarf::DW_LLE_base_address &&
326        E.Kind != dwarf::DW_LLE_base_addressx &&
327        E.Kind != dwarf::DW_LLE_end_of_list) {
328      unsigned Bytes = Version >= 5 ? Data.getULEB128(C) : Data.getU16(C);
329      // A single location description describing the location of the object...
330      Data.getU8(C, E.Loc, Bytes);
331    }
332
333    if (!C)
334      return C.takeError();
335    Continue = F(E) && E.Kind != dwarf::DW_LLE_end_of_list;
336  }
337  *Offset = C.tell();
338  return Error::success();
339}
340
341void DWARFDebugLoclists::dumpRawEntry(const DWARFLocationEntry &Entry,
342                                      raw_ostream &OS, unsigned Indent,
343                                      DIDumpOptions DumpOpts,
344                                      const DWARFObject &Obj) const {
345  size_t MaxEncodingStringLength = 0;
346#define HANDLE_DW_LLE(ID, NAME)                                                \
347  MaxEncodingStringLength = std::max(MaxEncodingStringLength,                  \
348                                     dwarf::LocListEncodingString(ID).size());
349#include "llvm/BinaryFormat/Dwarf.def"
350
351  OS << "\n";
352  OS.indent(Indent);
353  StringRef EncodingString = dwarf::LocListEncodingString(Entry.Kind);
354  // Unsupported encodings should have been reported during parsing.
355  assert(!EncodingString.empty() && "Unknown loclist entry encoding");
356  OS << format("%-*s(", MaxEncodingStringLength, EncodingString.data());
357  unsigned FieldSize = 2 + 2 * Data.getAddressSize();
358  switch (Entry.Kind) {
359  case dwarf::DW_LLE_end_of_list:
360  case dwarf::DW_LLE_default_location:
361    break;
362  case dwarf::DW_LLE_startx_endx:
363  case dwarf::DW_LLE_startx_length:
364  case dwarf::DW_LLE_offset_pair:
365  case dwarf::DW_LLE_start_end:
366  case dwarf::DW_LLE_start_length:
367    OS << format_hex(Entry.Value0, FieldSize) << ", "
368       << format_hex(Entry.Value1, FieldSize);
369    break;
370  case dwarf::DW_LLE_base_addressx:
371  case dwarf::DW_LLE_base_address:
372    OS << format_hex(Entry.Value0, FieldSize);
373    break;
374  }
375  OS << ')';
376  switch (Entry.Kind) {
377  case dwarf::DW_LLE_base_address:
378  case dwarf::DW_LLE_start_end:
379  case dwarf::DW_LLE_start_length:
380    DWARFFormValue::dumpAddressSection(Obj, OS, DumpOpts, Entry.SectionIndex);
381    break;
382  default:
383    break;
384  }
385}
386
387void DWARFDebugLoclists::dumpRange(uint64_t StartOffset, uint64_t Size,
388                                   raw_ostream &OS, const DWARFObject &Obj,
389                                   DIDumpOptions DumpOpts) {
390  if (!Data.isValidOffsetForDataOfSize(StartOffset, Size))  {
391    OS << "Invalid dump range\n";
392    return;
393  }
394  uint64_t Offset = StartOffset;
395  StringRef Separator;
396  bool CanContinue = true;
397  while (CanContinue && Offset < StartOffset + Size) {
398    OS << Separator;
399    Separator = "\n";
400
401    CanContinue = dumpLocationList(&Offset, OS, /*BaseAddr=*/std::nullopt, Obj,
402                                   nullptr, DumpOpts, /*Indent=*/12);
403    OS << '\n';
404  }
405}
406
407void llvm::ResolverError::log(raw_ostream &OS) const {
408  OS << format("unable to resolve indirect address %u for: %s", Index,
409               dwarf::LocListEncodingString(Kind).data());
410}
411
412char llvm::ResolverError::ID;
413